Method of producing denaturants of alcohol



@cih 1939- M. CHRISTENSEN METHOD OF PRODUCING DENATURANTS OF ALCOHOLFiled May 13, 195? Va 0 w); P1090 Fecal re Patented Get. 1?, i939 STATESME'rnon or rnonuomo DENA i F ALCOHOL Leo M. Christensen, Atchison, Kana,assignor to The Chemical Foundation, Incorporated, New York, N. Y., acorporation of Delaware Application May 13, 1937, Serial No. 142,340

7 Claims.

This inventionrelates to the production of denaturing compounds foremployment with industrial alcohol, more particularly to an improvedmethod of, and apparatus for, the production of B isonitriles.

The denatured alcohol employed in the in dustries is, as is known, ethylalcohol which is rendered unfit for beverage purposes and externalapplication by the addition of. a denaturant. I!) When properlydenatured, such alcohol is taxfree. Typical substances which have beenemployed in the past for denaturation are; methanol, benzine, Aldehol,ether, acetone, and the like, that is, substances with markedlydisagreeable odors and flavors, and poisonous properties.

The contemplated use of the industrial alcohol largely establishes ordetermines the particular type of denaturant employed. A substance whichis effective for denaturing alcohol for one par- .(i ticular use maybeentirely unsuited for denaturing alcohol intended for another use. Thusit isthat a large number of formulae, some eighty or more, have beengranted in this country for the preparation of denatured alcohol forvarious in- 5 dustrial uses.

A. tremendous potential use for alcohol is as a motor fuel. Blends of.alcohol and gasoline have long been employed as a motor fuel in Europe.In this country the potentiality of this 0 type of power fuel is rapidlybeing recognized and particularly as a method of economically utilizingdomestic farm products.

As has been explained in copending application Serial No. 85,181, filedJune 13, 1936, the em- 5 ployment of alcohol as a motor fuel presents aspecial problem in denaturation. A denaturant for power alcohol, inaddition to possessing the usual properties of a good denaturant, mustalso be of such a character that it will have no corrosive action on themetal of the engine and will not tend to form gums from constituents of.the hydrocarbon fuel with which it is blended. It furthermore shouldleave little or no residue upon distillation, as such residues wouldtend to de 5 posit in the valve seats and thus materially diminish theefiiciency of the motor.

As described in the copending application referred to, these desirablecharacteristics are found in the carbylamines, and particularly in i thealkyl carbylamines or alkyl isonitriles. These substances are colorlesssubstances freely soluble in alcohol andether, and slightly soluble inhydrocarbon oils. They have a characteristic, unbearable, putrid odorand are relatively toxic.

The several members of the series have boiling points within thedesirable range, that is to say boilingpoints closely approximating thatof ethyl alcohol. These compounds are so pungent that the addition ofeven minor amounts of them to ethyl alcohol most effectively denaturesit.

The extreme potency of these substances, while a marked advantage inuse, does, however, render the problem of. production exceedinglydiflicult. The isonitriles, in pure or highly concentrated form, havesuch a disgusting odor that it is substantially impossible to induceworkers to operate with them. In the concentrated form, furthermore,they are highly toxic. Finally, as would be expectable in view of theircharacteristics, they areextremely difficult to ship and therestrictions imposed on shipment render the shipping cost substantiallyprohibitive.

It has been found that these highly efficacious denaturants may be madereadily available for denaturation of power alcohol and the enumeratedobjections to the production of these compounds eliminated by a novelmethod of manufacturing the product. The broad concept of the presentinvention comprehends the idea of initially producing a solution ofisonitrile in a solvent such as alcohol. This is in sharpcontradistinction to prior methods in which the substantially pureisonitrile was first produced by known methods and was then dissolved inalcohol. Operating under the present invention, the isonitrile isformed, so to speak, in situ in a special vehicle and any desired degreeof dilution. By thus dissolving or extracting the isonitrile, orisonitrile mixture, from the moment of formation, the disadvantages ofproduction above mentioned are largely eliminated. The dilution of theproduct in situ thus enables the recovery of a solution which, whileeminently effective for the denaturation of alcohol, does not presentthe objectionable characteristics of the pure or highly concentratedisonitrile; that is to say, in the product produced by the presentmethod, the objectionable features are mitigated to such an extent as topermit commercial production of the product.

It is particularly to be observed that when operating under the presentinvention the mitigating vehicle, so to speak, which is employedperforms a number of functions in the method. In the first place thealcohol is employed as a reactant, functioning directly to effect thereaction. In the second place the alcohol serves as a solvent-diluentfor the isonitrile, reducing its obnoxious odor and toxicity to theextent that the product may be handled and shipped without unduedifilculty. Finally, the mitigating vehicle utilized constitutes theultimate material which is to be employed, namely a power alcohol.

The invention, therefore, may be considered to relate to the productionof a denaturant in power alcohol in which the denaturant is produced insitu in the alcohol, thus at the one time forming a denaturant andintimately blending it with the material with which it is to beultimately employed. This, again, is in sharp contradistinction ntoadistantblendingplant,

to prior methods of denaturation in which the i denaturant wasseparately. prepared and then shipped to some blending plant to be theretad-z mixed with the alcohol. Under the present 1 method: thedenaturantis formed directly in the I alcohol with which it istobeemployed.- :The ivention, therefore, may be equally Well defined as :amethod of producing a denatured alcohol con- :centrate which maybedirectly blendedzwith :ad-.

' utilizing a modified carbylamine' ;react-ion, that I ditionalquantities of alcohol, or'may beshipped.

Consonant i with the fundamental principle; of the present invention,that is the practical and I I safe production of denatured alcoholicconcenlisonitrile,-as formed, .is dissolved or extracted, in

any-desirably large quantity of a solvent-vehicle to produce'a denaturedalcohol concentrate which I may be readilyhandled. shipped and mediatelyor immediately blended withadditional quantities 'of'alcohol and/orgasoline; I

Incarrying out the process, the trile or mixture of isonitriles; isproduced by I is to say, by reacting primary amines withchloro- I i formto producethe corresponding alkyl cyanide I I wherein it representsanalkyl ;group.; I

I I be carried out by utilizing cheap technical; sodium.

I hydroxide rather than the: more expensive potassium hydroxide, as hasbeendone in the past;

In one form of the; invention; therefore, a suit-.

according to the followingequationz- I I 1 I I R,NH2+CHCI3* R.N#C I Thereaction is effected in the presence of al cohol. I It has been foundthat. this reaction may able primary amine (or mixture of amines) -is Icaused .to react with chloroform in the presence of at least astoicheometrical amount of sodium hydroxide and in the presence of amarked excess of ethyl alcohol. The reaction is carried out in a closedsystem and preferably with gradual additions of the chloroform to theprimary aminecaustic mixture.

After the reaction has run to completion, the alcoholic mixture isdistilled, preferably under reduced pressuraand the distillate,comprising the isonitrile dissolved in alcohol, is collected in a closedreceiver in which, if desired, it may be absorbed in additionalquantities of alcohol. The liquid product in the closed receiver maythen be transferred through a closed pipe system to a storage vessel,preferably by pneumatic pressure. In these circumstances, as will beappreciated, the isonitrile is taken up or extracted, as formed, in asolvent-diluent vehicle and co-distilled and transported with suchvehicle. As will be understood, the degree of dilution of the isonitrilemay be controlled and varied to any degree desired. The denaturantconcentrate thus produced may be piped directly to a blending plant tobe dissolved in additional quantities'of alcohol and/or asoline in theproportions desired for the ultimate use or, if desired, the concentratemay. be packed in suitable sealed containers for shipment.

In order to enable a more ready comprehension of the invention, asimplified apparatus in which the process may be effected is showndiagrammatically in the single figure of the accompanying drawing.

'By way of preliminary explanation, it is to be understood that it iswell known that primary alcorresponding alkyl-isocyanide.

action, knownas the carbylamine reactioznis the :to the still or reactorl in regulate-d amounts. associated a. heater 3 for the purpose ofheating I the reaction product to distillation temperatures.

; kylamines may be reacted with chloroform, in

the'presence of alcoholic potash, to produce the In fact this rethesecondary and In this typical carbylamine reaction but a and completethe reaction: i :Thus; when -substan:--

are: employed: for example 22.5 grams of mono- I small :amount-ofalcoholis necessaryto institute 'tially stoichiometrical amounts of the reagentamylamine, 31 grams or chloroform,-and 44. grams. I I t I i I i ofpotassium. hydroxide, less than .8 grams of I ethyl alcohol are requiredto effect the reaction.

' the past, asv indicated,- the'ca rbylamine reaction was utilized foranalytical work and, as I a I relatively pure or. concentratedisocyanide was desired, an excess of :alcohol was not. employed and. A

was not desirable. This reactioni-s to be careful,

alcohol is definitely established for the'purpose' I I I I :ofinsuringapositive and novelresult.

desired isonig- I In one phase: of the invention, therefore, .a primaryamine is reacted with chloroform. and

ztechnicalsodium hydroxide in the presence of a -markedexcess ofethylaicohol; i In operatingthe Y novel process for the denaturationofalcohol by I I I producingthe denaturant in situ in the alcohol,

the reagents are admitted inzany desired-sequence ing' a :control valve25, for admitting chloroform With the still i also is This element isprovided I I I I I :with .means, such as the dropping funnel .2, hav- Ina preferred procedure, chosen quantities of the I I I and the chloroformis admitted. slowly and .ini regulated amounts from the vessel 2.

As is known, the reaction described proceeds spontaneously andvigorously with considerable evolution of vapors. To insure completereaction the still is connected with a reflux condenser 4, through thevapor line 5, controlled by valve 5. The reflux condenser may be of anysuitable type. It is illustrated as a, simple liquid cooled worm ofconventional type. The worm may be positioned within any suitablecontainer 6, through which a cooling medium flows by way of the inletand outlet lines I and 8 respectively.

The reflux condenser is connected, by the overheadline 9, to thedistillation condenser II]. This, similarly, may be of any desired typeand of a size sufiicient to satisfy the requirements of the particularinstallation. Condenser 9 preferably is set within a container II and ispositively cooled by a cooling medium admitted through inlet I2 anddischarged through outlet l3.

The distillation condenser 9 is connected by the condenser line I4,controlled by valve [4, to the sealed container I5. The container IS, inturn, is connected to a receiver or storage vessel 1 through the line H,controlled by valve II. The line I6, it is to be observed, is connectedto a low point of the container l5; that is to say;

below the liquid level of the condensate collecting in container l5. Inthese circumstances the full hydrostatic head of liquid in thecontainer, in addition to any positive pressure imposed on the liquidsurface, is utilized for discharging the contents.

As indicated hereinbefore, a salient feature of" the present inventionis to eliminate handling of the product and to prevent the escape ofnoxious fumes or vapors. This is done not only by efiecting the reactionin a closed or sealed system, but also by efiecting the transfer of theproduct in a sealed circuit, in which circuit the isonitrile, o'risonitrile mixture, is absorbed in an absorbent vehicle.

For the purpose of transferring the alcoholisonitrile concentrate fromthe container l5 to the receiver l6, positive air pressure is utilized.As shown, the upper portion of the condensate container I5 is connectedthrough the line l8, controlled by valve I8, to the compressor [9.Interposed in the line i8 is a gauge 20 for indicating the pressure orvacuum obtaining during the operation. With this type of construction,the compressor may be operated to impose any desired degree of pneumaticpressure on the condensate in container l5 and thus readily force suchcondensate through a closed pipe line to storage.

As will be appreciated, the present treatment is carried out in twosteps or stages. In the first stage the reagents react according to thefollowing equation:

As the reagents interact, the vapors evolved are condensed incondenser 6and reflux condensate flows back into the still. The desired reactionproduct, that is the alkyl isonitrile in solution in alcohol, is thenrecovered by distillation.

To avoid any decomposition of the isonitrile the distillation ispreferably carried out at a reduced pressure, and the distillation is socontrolled as to produce a substantially homogeneous distillatecomprised essentially of isonitrile dissolved in alcohol.

The distillation under reduced pressure may be accomplished, as will beappreciated by those skilled in the art, by utilizing any suitable typeof apparatus. That shown in the drawing is merely illustrative of anysystem which is effective to establish a reduced pressure in the stilland to enable a low temperature distillation. As shown, a source ofsuction or vacuum, such as a vacuum pump 2 l, is connected through asuitable trap system, such as traps 22, 23 and 24%, to the distillationapparatus. In the particular apparatus chosen for illustration thevacuum line 25, having the control valve 25, communicates with the linel8 and thence with the container l5. Manifestly, however, suchconnection may be made at any other suitable point in the system.

Similarly, in lieu of the vacuum pump 2|, any

. other apparatus which is efi'ectiveto establish a reduced pressure inthe distillation system may be used. Thus, in lieu of the vacuum pump,an eduotor unit may be utilized. For example, a high velocity stream ofalcohol may be forced through an eduotor or inspirator, the suctioninlet of which is connected to line M, and the discharge from whichempties into container l5. In the operation of this type of structurethe high velocity stream of alcohol passing through the eductor inducesor establishes a reduced pressure in line l6, condensers l and '5 andstill i. This high velocity stream also functions to condense and absorbthe evolved vapors of isonitrile andalcohol.

Any other type of apparatus functioning in an equivalent manner may beemployed. The precise operations carried out under the present methodwill have been appreciated from the foregoing concentrate is produced.The concentrate condescription. Thus for the-preparation, for ex--ample, of a denaturant concentrate of alcohol and amyl isonitrile, thefollowing operation may be carried out. A charge comprisingapproximately 1000 grams of technical sodium hydroxide (76%), 542 gramsof mixed monoamylamine and 920 grams of ethyl alcohol is admitted to thestill. It is to be observed that the quantity of alcohol here employedis approximately five times the theoretical amount actually required.The still I is then closed, valve 5' is opened and chloroform is addedslowly from the funnel 2. The flow of chloroform is preferablycontrolled so as to maintain the reaction mass in a state of gentleebullition. After the addition of all of the chloroform, the reactionmixture is allowed to reflux for a period of thirty minutes more orless, that is until the reaction has ceased. During this period theevolved vapors are condensed-in reflux 6 and the condensate drained backto the still. The temperature and velocity of the cooling medium. forthe condenser are controlled so as to secure efiicient condensation, inthe manner known to those skilled in the art.

After the reaction has ceased and all condensate is drained fromcondenser E to the still, conditions are adjusted to insuredistillation. For this purpose valves 25 and Hi are opened (valve I8being closed) and the pump 2| is operated to establish a reducedpressure in the distillation system i6-IB-I5. The reaction mixture isthen heated, by heater 3, to distillation temperatunes and the mixturedistilled to dryness.

In these circumstances a mixture of alcohol, isonitrile and water vaporis evolved and condensed in condenser ill. The total condensate flowsthrough line M to container l5. After the completion of the distillationcycle the vacuum pump is stopped and the vacuum. in the system released,as for example through valve 2.

The condensate in tank I5 is then forced to receiver l6 where, ifdesired, it may be absorbed in or blended with additional quantities ofalcohol. To effect this transfer valves I l and 25' are closed andvalves H and it are opened. The compressor I 9 isoperated and thepneumatic pressure thus developed is utilized to' force the denaturantconcentrate through line ii to receiver IE, or to any other unit of theplant. When the condensate in tank I 5 has been discharged, the valve i8is closed and the pressure in the tank I5 is relieved through line Horany v suitably positioned blowoif valve.

In practise it is preferred to cleanse the still prior to each reactioncycle. For this purpose the still may be flushed with a suitablecleansing medium, such for example as dilute sulphuric acid. The acidmay then be removed and the still flushed with water or other suitablefluid so as to thoroughly cleanse it prior to the next cycle.

Operating under the conditions described above, and with the quantitiesof materials indicated, approximately 4 lbs. of isonitrile-alcohol tainsapproximately 35% of impure isonitrile. As noted hereinbefore, thequantity of isonitrile in the concentrate may readily be varied byutilizing a greater excess of alcohol. Furthermore, as described, theconcentration of the isonitrile may be further diminished by absorbingthe distillate in additional quantities of alcohol in receiver l6.

It is particularly to be observed that, when operating under theprinciples of the present method, the final product recovered from theclosed system is a solution of the isonitrile in the alcohol with whichit is to be used. The process may be carried out so as to control theconcentration of the isonitrile at all times and at all stages of theprocess. This advantage, coupled with the fact that the entire reactionand blending is carried out in a closed or sealed system, eliminates thepersonal hazards and acute discomfort which heretofore attended theproduction of similar products.

The present method presents other potential advantages. For example,this method is ideally suited to the production of special blends ofdenaturants of the type described in copending application Serial No.122, 17 8, filed Jan. 26, 1937. A denaturant concentrate of anisonitrile, or

mixture of isonitriles, with methanol, acetone,

and the like, may readily be produced in this system. For this purposemethanol may be admitted to the still I at the termination of thereaction period, and may be co-distilled with the ethyl alcohol andisonitrile to produce an intimately blended concentrate. Again, ifdesired, the methanol or other denaturant may be admitted to the streamof the alcohol-isonitrile condensed in transit to the receiver I 6. Yetagain the supplemental denaturant may be primarily admixed with thevapors passing through line 9 or condenser II] to be intimately blendedwith these vapors while at the same time functioning as a condensingagent. In short, the additional denaturant may be intimately blendedwith the main concentrate at any suitable stage in the system and ineither the vapor or liquid phase.

While, for the purpose of explaining the invention, the conversion of aparticular alkylamine (amylamine) has been described, it will beunderstood that this is merely illustrative and that other isonitrilesmay be produced in the same manner and in the same apparatus; it isequally apparent that a mixture of such isonitriles may besimultaneously produced.

It is further to be observed that the present system may be utilized,whenever it is desired, for the production of relatively pureisonitriles. In these circumstances a type of reaction described may becarried out in which the amount of alcohol is reduced to substantiallythat theoretically required. After reaction the isonitrile may bedistilled and recovered in receiver I5. The condensate may be allowed tosettle in tank l5, or may be transferred to receiver It, so as to permitstratification and separation of the aqueous from the isonitrilelayer.The separated isonitrile may then be removed and passed to suitablestorage or otherwise disposed of.

It is to be noted that in this type of operation the major advantages ofthe utilization of a closed system are retained; that is to say, byutilizing the principles of the present invention, relatively pureisonitriles may be produced without the disadvantages of the oldermethods. The relatively pure isonitrile, while still maintained in aclosed circuit, may be dissolved in alcohol or other solvent forutilization as a denaturant,

While preferred modifications of the invention have been described, itis to be understood that these are given to illustrate the underlyingprinciples and as indicating the great flexibility of the process andthe wide permissive range of products obtainable. The invention is notintended to be limited to the particular methods or products described,except as such limitations are clearly imposed by the appended claims,

I claim:

l. A method of denaturing ethyl alcohol which comprises, producing analkyl isonitrile in a closed system and in contact with a portion of thealcohol to be denatured, then blending the resulting alcohol-isonitrileconcentrate with the remaining ethyl alcohol to be denatured.

2. A method of producing denatured ethyl alcohol which comprises,producing an alkyl isonitrile from the corresponding alkyl amine in aclosed system and in the presence of a marked excess of alcohol,co-distilling and co-condensing the isonitrile and alcohol in a closedsystem, and forcing the resulting concentrate through a closed circuitto the receiver and blending additional ethyl alcohol, to be denatured,with the concentrate in said closed circuit.

3. A method of producing denatured ethyl alcohol which comprises,producing an alkyl isonitrile from the corresponding alkyl amine in aclosed system and in the presence of a marked excess of alcohol;co-distilling and co-condensing the distillable and condensable reactionproducts in a .closed system and forcing the resulting concentratethrough a closed circuit to a receiver, and blending the concentratewith additional ethyl alcohol in such receiver.

4. A method of producing denatured ethyl alcohol which comprises,producing the desired alkyl isonitrile from the corresponding alkylamine in a closed system and in the presence of a marked excess ofalcohol, co-distilling the formed isonitrile and alcohol under a vacuum,co-condensing the vapors of isonitrile and alcohol in a closed condenserand forcing the condensate, under pneumatic pressure, through a closedcircuit to a receiver, and blending the concentrate with additionalethyl alcohol to be denatured.

5. A method of producing denatured power alcohol, which comprises,reacting a primary alkyl amine with chloroform, caustic soda, and anexcess of ethyl alcohol to produce the corresponding alkyl isonitrile;distilling the reaction products, and recovering the alkyl isonitrilesin solution in the quantity of alcohol employed in the reaction, andblending such concentrate with additional ethyl alcohol to be denatured.

6. A method of producing denatured power alcohol, which comprisesreacting a primary alkyl amine with chloroform and caustic soda, in aclosed system and in the presence of a marked excess of ethyl alcohol;co-distilling and co-condensing the volatile reaction products togetherwith the excess of ethyl alcohol in a closed distilling and condensingsystem, and blending additional ethyl alcohol to be denatured with thesaid condensed reaction products in the system,

'7. A method of producing denatured ethyl alcohol to produce a poweralcohol-fuel which comprises, reacting a primary amine with chloroformand with caustic soda, in the presence of the ethyl alcohol which is tobe denatured, co-distilling and co-condensing the volatile andcondensable reaction products together with such excess alcohol, andblending the condensate thus produced with additional quantities ofalcohol to be employed as a fuel.

LEO M. CHRISTENSEN.

